Every modern Linux distribution has some kind of package manager that simplifies the process of finding, downloading, and installing software. So the relevant questions are:
1. what is your Linux's package manager
2. do you have sufficient privileges to use it
3. can you use it to search for a package that provides ncurses, curses, or termcap
4. if such a package exists, can/how do you use the package manager to download and install the package?

For example, I'm using CentOS, which offers yum (command line) and pirut (a GUI tool) as package managers, so if I lacked ncurses, curses, or termcap, I'd use yum or pirut to download and install one or more of them.